Here’s my translation

Alan

Hörðr hljóp í milli fóta honum.
Hörðr leapt between his (Skjöldr‘s) legs.

Ok vó hann upp á baki sér ok rak hann niðr fall mikit.
And lifted (vega, Z1) him up on his back and drove him down violently (lit: a great fall).

Losnuðu þá hendr Skjaldar af stönginni.
Then (the) hands of Skjöldr became-free from the staff.

Þá kom gradhestrinn ok greip í hárit á Herði með tönnunum ok sykti honum til falls ok dró hann eptir sér.
Then the-entire-horse (ie stallion) came and gripped into the-hair on Hörðr with the (his, its)-teeth and made-him-sink (sökkva?) to a fall (ie forced him down) and dragged him behind himself/itself

Hrossin öll komu þangat ok vildu bíta Hörð.
All the horses came thither and wanted to bite Hörðr.

Hann komst seint á fætur, en hvar sem þau kiptu til hans þá festi hvergi tennrnar á honum, en ef þau slogu til hans þá kiptu sjálf fótunum ok lysti eigi at slá optar enn um sinn.
He made-his-way slowly to (his) feet, but wherever they (the horses) snatched at him then the-teeth fastened nowhere on him, but (and) if they struck (aimed a blow) at him then (they) themselves (sjálf, nom neut pl) pulled the-(their own) feet (tripped themselves up?), and (they) desired (lysta) not to strike more-often than (enn = en) once (um sinn).

Skjöldr hleypr þá þangat.
Skjöldr runs then thither.

Þá kom Knútr fram úr skóginum.
Then Knútr came forward out-of the-forest.

Hleypr þá til móts við Skjöld.
(He) runs then to a meeting with (ie towards) Skjöldr.

Skjöldr laust þá til hans með stönginni.
Skjöldr smote then at him with the-staff.

En hann laust í móti með kylfunni.
But (And) he smote in return with the-club.

Ok var þá hvárgi þeira svá næri öðrum at eigi mátti höggunum við koma.
And then neither-of-the-two of them was so near to (the) other that (they) could not bring the-blows against (them) )ie they were to close too each other to deliver effective blows, presumably double negative of emphasis?)

Gripust þeir þá ok váru þá harðar sviptingar.
They seized-one-another then and hard tussles then were (ie took place)

Eigi mátti Hörðr honum björg veita þvíat hrossin óþægðu honum, en hann ók við hlaununum ok vildi þeim eigi mein gjöra.
Hörðr could not grant him help because the-horses vexed him, but (and) he drove (aka) against the (their) haunches and wanted not to do harm to them.

Þeir Knútr ok Skjöldr gengust nú at svá at þursinn óð jörðina til knjá.
They, Knútr and Skjöldr, engaged now in a fight (gangast, Z16), such that the ogre-giant waded the-earth to (the) knee (was knee deep in the earth)

Ok varð Knútr sýnt orkuvana fyrir honum.
And Knútr became clearly bereft-of-strength before (because of, ahead of, in his presence?) him.

Þessu næst kom Stígandi fram úr skóginum með svínaflokkinn.
In this next (instant) Stígandi came forward out-of the-forest with the-herd-of-swine.

Hann sneri þangat til sem þeir áttust við Skjöldr ok Knútr.
He turned (went) thither where they, Skjöldr and Knútr, fought-one-another (eigast við, recipr., Z)

Hann krækti svíðunni í huppinn á Skildi ok sökk hon á kaf.
He hooked the-bill-hook into the-loins of Skjöldr and it (the bill-hook) sank deep.

Hann rykkti at sér ok skar út úr ok lágu þar þarmarnir.
He jerked (it) to himself and cut out out-from (the loins) and the-intestines lay there (ie were exposed).

Röktust þeir þá úr honum ok lágu þar á króknum.
They (ie the intestines) were-raked (guessing passive form of raka with weak verb type 1 conjugation?) then out-of him and lay there on the-hook

Fellu þá út iðrin.
Then the-bowels fell out.

Hann greip þá í eyrat á Knút ok reif þat af honum.
He (Skjöldr) gripped then into the-ear on Knútr and tore that (ie the ear) off him.

Fell Skjöldr þá.
Skjöldr then fell.

Þá kom Hörðr at ok rasaði sér ofan á hann ok svá á brjóstit á honum, ok brotnaði þá í honum hvert bein.
Hörðr then came towards (them) and rushed himself down on him and thus on to the-breast of him, and each bone in him (Skjöldr) then was-broken.

Var nú unnin þessi þraut.
Now this-struggle was done-and-won.

En þeir váru bæði sárir ok móðir.
But (And) they (Knútr and Hörðr) were both wounded and tired.

Dreifðu þeir þá öskunni yfir hrossin.
They scattered then the-ashes (aska) (from the little-bag) over the-horses.

Flókatrippit hljóp undan.
The-filly-foal-with-the-matted-coat ran away.

Komust þeir Knútr ok Hörðr hvergi á mitt skeið við hana.
They, Knútr and Hörðr made-their-way nowhere to (a) middle way with her (ie they were not able to intercept her)